Electromagnetic control mechanism for electric shutter

ABSTRACT

An electromagnetic control mechanism for an electric shutter of a camera. The shutter-operating mechanism is controlled by a biased control lever which is linked to the armature of an electromagnet that controls release of the control lever which releases the shutter-operating mechanism for closing the shutter. A pressure-applying member applies a biasing force or pressure to the armature urging it to its attracted position which is maintained by the electromagnet when energized prior to removal of this pressure force. The application of this pressure force eliminates any effect of &#39;&#39;&#39;&#39;play&#39;&#39;&#39;&#39; in the mechanical connection between the armature and the biased control lever, which is released by the electromagnet when de-energized, so that a smooth, positive and precise closing of the shutter is effected.

[ Oct. 2, 1973 [22] Filed:

[ ELECTROMAGNETIC CONTROL MECHANISM FOR ELECTRIC SHUTTER [75] Inventor: Kiyoshi Kitai, Tokyo, Japan [73] Assignee: Seiko Koki Kabushiki Kaisha,

Tokyo, Japan Dec. 18, 1972 [21] Appl. No.: 315,847

[30] Foreign Application Priority Data Dec. l6, 1971 Japan 46/102125 [52] U.S. Cl 95/53 EB, 335/219, 335/277 [51] Int. Cl G03b 17/00, HOlf 3/00 [58] Field of Search 95/53 EB, 53 EA,

95/53 R, 53 E, 10 C, 10 CT; 335/219, 238, 249, 270, 271, 274, 276, 277

Sohn 95/53 EB X Fahlenberg et al. 95/53 EB Primary Examiner-Joseph F. Peters, Jr. Attorney-Robert E. Burns et al.

[57] ABSTRACT An electromagnetic control mechanism for an electric shutter of a camera. The shutter-operating mechanism is controlled by a biased control lever which is linked to the armature of an electromagnet that controls release of the control lever which releases the shutteroperating mechanism for closing the shutter. A pressure-applying member applies a biasing force or pressure to the armature urging it to its attracted position which is maintained by the electromagnet when energized prior to removal of this pressure force. The application of this pressure force eliminates any effect of play in the mechanical connection between the armature and the biased control lever, which is released by the electromagnet when de-energized, so that a smooth, positive and precise closing of the shutter is effected.

5 Claims, 4 Drawing Figures PATENTEIJIIBT 2M5 3.752.29

sum 10F 2 F/./'; Flaz (PRIOR ART) ELECTROMAGNETIC CONTROL MECHANISM FOR ELECTRIC SHUTTER BACKGROUND OF THE INVENTION shutters used in cameras for taking exposures are well known. In some of these control mechanisms, a control member, for example a control lever, is used to control initiation of the termination of an exposure time upon de-energizing of an electromagnet. The control member is connected to the armature of the electromagnet and is biased for initiating the control of shutteroperating mechanisms for closing the shutter upon deenergization of the shutter, and at the same time retracting or moving the armature away from its attracted position.

In this type of control mechanism, a pressureapplying member is used to apply a biasing force or pressure to the armature in a direction toward its attracted position and against the biasing force applied thereto by the control mechanism tending to move the armature away from its attracted position. Moreover, a connection between the control mechanism, and more particularly, the control lever of this mechanism, and the armature generally have a certain amount of play therein such that the shutter-operating mechanism in opening the shutter for taking an exposure may affeet the pressure-applying member so that it delivers a mechanical impulse to the armature which may tend to actuate the armature in a direction away from its attracted position after it has been attracted by the electromagnet. Accordingly, the electromagnet, once energized, must be sufficiently strong enough to overcome the biasing force of the control lever and this mechanical impulse might otherwise cause an inadvertent release of the armature thereby prematurely terminating the exposure time when an exposure is being taken.

SUMMARY OF THEv INVENTION It is an object of the present invention to provide an electromagnetic control mechanism or arrangement in electrically energizable electromagnet having an armature which is released upon de-energization of the electromagnet for effecting shutter operations such as closing the shutter, and thereby terminating an exposure time. A control member, for example a control lever is connected to the armature initiating the closing of the shutter upon completion of exposure time upon deenergization of the electromagnet. This control means is biased in a direction for initiating closing of the shutter and in a direction for moving the armature away from its attracted position. A pressure-applying lever or means applies pressure to the armature directly in a direction to maintain it in its attracted position. This pressure-applying means is independent of the control lever.

The application of this pressure maintains a firm and positive mechanical connection between the control means actuating the armature so that upon release of the armature, a smooth operation is maintained without mechanical impulses.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic elevation view of a known electromagnetic control mechanism for an electric shutter;

FIG. 2 is a diagrammatic elevation view of a shutter of the type shown in FIG. 1 provided with the invention;

FIG. 3 is a second embodiment of an electromagnetic control mechanism for a shutter according to the invention; and

FIG. 4 is a fragmentary elevation view of an electromagnetic control mechanism for an electric shutter for a camera according to the invention.

Other objects and advantages will appear from the following description of an example of the present invention, and the novel features will be particularly pointed out in the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a well known electromagnetic control mechanism for an electric shutter of a camera is disclosed. As can be seen in the drawings, a driving plate or cam 1, pivotally mounted on a shaft 2, is biased in a counterclockwise direction by a spring 3 for opening and closing a shutter as hereinafter explained. A pivot 4 about which is wound a biasing spring 5 pivotally supports a lock lever 6 which is biased in a clockwise direction by the biasing spring 5 so that it engages a notch or shoulder formed on a cam surface la of the driving plate 1 to releasably hold the driving plate or cam l in a position as illustrated in FIG. l which constitutes a condition corresponding to the cocked or charged condition of an electric shutter, not shown, with which this mechanism is associated.

An operating lever 7 pivotally mounted on a pivot 8 actuates shutter blades, not shown, to an open and closed position. The operating lever 7 is provided adjacent one end thereof with a pin 9 having a semicircular cross section. A crank lever 10 is pivotally mounted on a pivot l 1 supported on the driving plate 1 and is biased by a spring 12 in a clockwise direction. The pin of the operating lever 7 engages a notch 10a on the crank lever 10 and configured as illustrated.

A control lever 13 is pivotally mounted on a pivot 14 and is biased in a counterclockwise direction by a spring 15. The control lever is provided with a pin 16 connecting it to an electromagnet armature 17 which has an opening 17a into which the pin 16 extends. A clearance lexists between the pin and the aperture providing play" in the connection. A plate spring 18 is mounted or riveted with rivets 19 on the control lever 13 and cooperates with a cam surface 1a of the driving plate or cam l for applying a counterforce to the control lever 13 against the action of its biasing spring 15 and applying its force in the direction of maintaining the armature in its attracted position. In the position of the elements illustrated in FIG. 1, the shutter is in a cocked condition and the plate spring 18 is biased or deflected so that the counterforce is developed.

The lock lever 6 is released when the release lever, not shown, of the camera is actuated so that the driving plate or cam 1 is rotated by its biasing spring counterclockwise so that a notch 1b thereon engages a tip 13b of the control lever 13 and the driving cam is precluded from continuing its rotation. During its partial rotation, the driving cam l actuates the shutter blade operating lever 7 so that the blades of the shutter, not shown, are actuated to an open position.

In the cocked condition, the armature 17 is biased by the plate spring 18 to its attracted position in its electromagnet 20, however, when the driving cam l rotates in its initial phase of rotation, the cam surface In thereof is rotated out of its position in which it contacts the plate spring 18 so that the biasing force on the armature is not developed. However, switch means in the electrical circuitry, not shown, of the shutter has been controlled so that the electromagnet 20 is electrically energized and retains the armature 17 attracted and the control lever 13 is maintained in the position shown in the cocked condition.

When the electromagnet is de-energized, for example as a function of the brightness of a scene being photographed, the electromagnet 20 is de-energized and the control lever is released so that its biasing spring rotates it in a counterclockwise direction so that the driving cam 1 is freed from its temporarily locked position and the driving cam rotates further so the exposure time is determined or terminated since the further rotation of the driving plate or cam 1 actuates the shutter to a closed position and an exposure is completed. The mechanism is restored to a cocked condition by means not shown.

The movement of the cam 1 or rotation thereof through its initial phase causes a mechanical impulse to be applied to the armature in view of the play 1. Accordingly, the electromagnet must be sufficiently strong to retain the armature attracted against the mechanical impulse applied and the force of the biasing spring 15 to avoid premature release of the armature which would result in an improper exposure.

According to the invention, the development of this mechanical impulse is avoided. Thus, in the electromagnetic shutter mechanism illustrated in FIG. 2, the parts corresponding to those of the mechanism in FIG. 1 have the same reference numerals. However, in this instance, a pressure-applying lever 21 is pivotally mounted on the pivot 14 coaxially with a control lever 13 so that the control lever and this pressure-applying lever are different from the structure of the firstdescribed embodiment. In this case, moreover, the plate spring 18 is mounted on the pressure-applying lever 21 so that it applies a pressure force or biasing force directly on the armature l7 urging it toward its attracted position. The application of this pressure eliminates the play between the aperture 17a and the control lever pin 16 on the side of the connection thereof toward the pressure-applying lever 21 as illustrated in the drawing. The removal of this clearance eliminates the development of a mechanical impulse during the initial and second phases of rotationof the cam 1, which is actuated in the manner described heretofore with respect to the first embodiment. Otherwise,

the mode of operation of this embodiment of the invention is exactly as that described heretofore.

A second embodiment of an electromagnetic control mechanismfor an electric shutter embodying the invention is illustrated in FIG. 3. In this embodiment, the electric shutter opens and closes a lens aperture 60 provided on a camera, not shown. The shutter is illustrated in the drawing in a charged or cocked state in which an opening shutter plate 61 closes the lens aperture 60 and is biased upwardly by a spring 62. It is provided with a projection 61a engaged by a lock lever 63 pivotally mounted on a pivot 64 and biased in a clockwise direction by a biasing spring 65 to maintain the opening shutter plate 61 in the position shown. The opening plate is provided with an aperture 61b for registry with the lens aperture for taking an exposure when a photograph or exposure is to be taken as later described.

A pivot 66 on the opening plate pivotally mounts a pressure-applying lever 67 which is biased in a clockwise direction by a spring 68 and directly applies pressure to an armature 69 of an electromagnet 70 biasing it in the direction of its attracted position. A closing plate 71 has an aperture 71a in registry with the lens aperture of the camera when the shutter is closed in the charged state or cocked condition illustrated in FIG. 3. The closing plate 71 is biased upwardly by a spring 72 and is provided with a pin 73 received in an opening 69a of the armature 69 providing a mechanical connection therewith and play as illustrated. However, in view of the force applied by the pressure-applying lever 67, the play clearance is on the lower side of the pin 73 and is eliminated with respect to the movement of the closing plate 71 when released by the electromagnet.

When the camera release lever, not shown, is actuated for taking an exposure, it releases the lock lever 63 which releases the closing plate 61 and it moves upwardly under the control of the spring 62 for opening the shutter. The pressure-applying lever 67 disengages from the armature 69 as the opening plate moves upwardly, however, this happens subsequently to the electrical circuitry, not shown, of the shutter energizes the electromagnet 70 so that the armature is retained in an attracted condition. When the electromagnet is deenergized, by circuitry controlling the time exposure period, the armature is released and the closing plate 71 is thereby released and it moves upwardly under the control of the spring 72 closing the shutter completing the exposure. The mechanical connection between the armature and the closing plate 71 is a positive connection free of any effect of the play as before described.

A third embodiment, an electromagnetic control mechanism for a shutter embodying the invention is illustrated in FIG. 4, fragmentarily. In this instance, the shutter driving cam and other associated elements can be constructed as illustrated in FIGS. 1 and 2. In this embodiment a shutter release lever 81 is provided and it is provided with elongated slots within which guide pins are received for guiding axial movement of the release lever 81 when depressed for taking an exposure. It is constantly biased upwardly by a biasing spring 82 and is depressed downwardly for taking of an exposure. A pivot 83 alongside thereof pivotally mounts a pressure-applying lever 85 which is biased in a counterclockwise direction. The release lever is provided with a pin 86 which engages the pressure-applying lever 85,

when the release lever is pressed downwardly, to rotate it in a clockwise direction as hereinafter described. In the cocked condition of the shutter illustrated in FIG. 4, the pressure-applying lever 85 applies pressure directly onto an armature 87 of an electromagnet 88 and urges the armature in the direction of its attracted position.

A control lever 91 corresponding to the control lever 13 of the embodiment shown in FIG. 1 is pivotally mounted on a pivot 89 and is biased in a counterclockwise direction by a biasing spring 90. The control lever is provided with a pin 92 received in an aperture 87a of the armature. As can be seen, the application of pressure by the pressure-applying lever 85 on the armature eliminates any clearance between the pin 92 and the control lever and the armature opening 87a on the right-hand side of the connection, as illustrated in the drawing.

When the release lever 81 is operated to take an exposure, the pin 86 is moved downwardly and engages the pressure-applying lever. As the release plate moves downwardly, a switch, not shown, is closed in the initial period of movement to energize the electromagnet 88 and thereafter the pin 86 contacts the pressureapplying lever 85 making it rotate clockwise so it releases the armature 87 with respect to the mechanical pressure force applied thereto. However, since the armature has already been attracted and it is releasably held by the electromagnet 88, the armature maintains the control lever 91 at its initial position until the electromagnet 88 is de-energized, in which case it then releases the armature and the control lever rotates to allow the exposure time to be determined. Since the electromagnet retains the initial conditions until deenergized, the effect of the play in the mechanical connection between the pressure-applying lever 85 and the armature 87 is eliminated as is the case in the other two embodiments of the invention.

What I claim and desire to secure by letters patent is:

1. An electromagnetic control mechanism for an electrically-operated shutter for a camera comprising, an electrically energizable electromagnet for initiating the closing of a shutter upon de-energization thereof, said electromagnet comprising an armature, pressureapplying means applying pressure on the armature when the shutter is in a cocked condition biasing the armature to an attracted position thereof, control means releasably held by the electromagnet biased in a direction for initiating closing of said shutter when the shutter is in a cocked condition and releasably controlled by said electromagnet, connection means connecting the control means to said armature with some degree of play in the connection, and said pressureapplying means being disposed to apply pressure directly on the armature and in a direction eliminating any effect of the play in said connection, whereby when the electromagnet is de-energized the control means is released and closing of said shutter is initiated.

2. An electromagnetic control mechanism according to claim 1, in which said control means comprises a lever biased for movement from a rest position toward a position away therefrom for initiating closing of said shutter, and means to nullify the application of said pressure before said electromagnet is tie-energized.

3. An electromagnetic control mechanism according to claim 2, in which the last-mentioned means comprises a release lever.

4. An electromagnetic control mechanism according to claim 2, in which the last-mentioned means comprises a shutter plate mounting said pressure-applying means.

5. In a shutter having a shutter-operating mechanism having means for opening and closing a shutter, an electromagnetic control mechanism for initiating at least closing of said shutter comprising, a control member coactive with said shutter-operating mechanism for controlling and initiating the closing of a shutter by said shutter-operating mechanism, an electrically energizable electromagnet having an armature releasably holding the control member when energized and releasing it upon de-energization thereof to control initiation of closing of said shutter to terminate an exposure period, means biasing the control member toward a direction for initiating closing of said shutter, and pressure-applying means applying a force on said armature toward its attracted position when the electromagnet is in a de-energized condition and an exposure is not being taken and having means effectively removing the force at least when the electromagnet initiates termination of said exposure period. 

1. An electromagnetic control mechanism for an electricallyoperated shutter for a camera comprising, an electrically energizable electromagnet for initiating the closing of a shutter upon de-energization thereof, said electromagnet comprising an armature, pressure-applying means applying pressure on the armature when the shutter is in a cocked condition biasing the armature to an attracted position thereof, control means releasably held by the electromagnet biased in a direction for initiating closing of said shutter when the shutter is in a cocked condition and releasably controlled by said electromagnet, connection means connecting the control means to said armature with some degree of play in the connection, and said pressureapplying means being disposed to apply pressure directly on the armature and in a direction eliminating any effect of the play in said connection, whereby when the electromagnet is de-energized the control means is released and closing of said shutter is initiated.
 2. An electromagnetic control mechanism according to claim 1, in which said control means comprises a lever biased for movement from a rest position toward a position away therefrom for initiating closing of said shutter, and means to nullify the application of said pressure before said electromagnet is de-energized.
 3. An electromagnetic control mechanism according to claim 2, in which the last-mentioned means comprises a release lever.
 4. An electromagnetic control mechanism according to claim 2, in which the last-mentioned means comprises a shutter plate mounting said pressure-applying means.
 5. In a shutter having a shutter-operating mechanism having means for opening and closing a shutter, an electromagnetic control mechanism for initiating at least closing of said shutter comprising, a control member coactive with said shutter-operating mechanism for controlling and initiating the closing of a shutter by said shutter-operating mechanism, an electrically energizable electromagnet having an armature releasably holding the control member when energized and releasing it upon de-energization thereof to control initiation of closing of said shutter to terminate an exposure period, means biasing the control member toward a direction for initiating closing of said shutter, and pressure-applying means applying a force on said armature toward its attracted position when the electromagnet is in a de-energized condition and an exposure is not being taken and having means effectively removing the force at least when the electromagnet initiates termination of said exposure period. 